Tagged Questions

Collision detection is the determination of whether or not two or more entities make contact with each other during gameplay.

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4
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3answers
4k views

How to handle platform collisions in a 2D game?

If I have a map in my platformer game and I want my character be able to jump on some platform, for example. Is there an easy way to tell the game where the platforms are and where the player can jump ...
1
vote
1answer
2k views

How can I cancel a contact in a b2ContactListener?

To know when contacts happen we can derive from b2ContactListener and implement our own solution which is great. I'm wondering is there anyway we can cancel a contact, that is to say when we hit begin ...
11
votes
3answers
4k views

Collision resolution in case of collision with multiple objects

I have static objects and movable objects. The collisions are detected using the separating-axis-theorem. For example, in this situation I have two static objects (in red): and a movable object ...
1
vote
1answer
814 views

Can you help with collision detection and response in a 3D car racing game?

I am trying to implement the collision detection and response in 3D car racing game. I have a car model, for collision I am assuming my car as a cuboid. my collision detection with walls is quite ...
22
votes
4answers
2k views

Momentum and order of update problems in my physics engine

This question is a "follow-up" question from my previous one, regarding collision detection and resolution, which you can find here. If you don't want to read the previous question, here's a ...
0
votes
2answers
499 views

C# XNA Framework Paddle Collision Problems

I am trying to make a pong game that uses a burger as a ball and a plate as its paddle. I have everything right except that the burger goes right through the plate. Can anyone help me? using System; ...
0
votes
2answers
898 views

How to coordinate sprites, player's position and collisions in a Bomberman-like 2D game?

I'm programming a Bomberman in Java (my first game) and I'm having problems with the player's sprites and position in the map. I'm using a 2D integer array to represent: Unbreakable blocks ...
8
votes
2answers
2k views

pathfinding with obstacles in a Warcraft 3 like game

Consider A* searching on a tile based map. A straight forward code would be: If there is an unit inside that cell, then it is unreachable, this is ok. But there is map resolution issue. When I look ...
5
votes
2answers
1k views

Checking for Weapon Collision in a 2D overhead RPG game

I'm starting development on a 2D overhead RPG game, and am wondering what the best approach for handling weapon collision and dealing damage to enemies is. I'm currently using a basic ...
2
votes
1answer
587 views

Need help with collision detection/resolution in a 2D simulation of 'worm-like' creatures

(originally posted this on regular stack overflow, somebody pointed this forum out :-) ) Hi there, I'm implementing a physics engine for the simulation of worm-like creatures. Problem is, is that ...
2
votes
2answers
502 views

Best way to traverse triangles in a mesh

I'm implementing non-projective decals. As described in many places (ie: lengyel in the gpg2) I first need to detect all triangles that lie within some sort of frustum. Besides obvious brute-force ...
1
vote
1answer
919 views

Android Fling Gesture, Animation And Collision - Resources?

I'm starting work on a 2D Android game where the player will put their finger on a game piece and do a fling gesture to throw the piece across the gameboard. I've gone through some Android ...
11
votes
2answers
13k views

Is there a good way to get pixel-perfect collision detection in XNA?

Is there a well-known way (or perhaps reusable bit of code) for pixel-perfect collision detection in XNA? I assume this would also use polygons (boxes/triangles/circles) for a first-pass, quick-test ...
2
votes
2answers
8k views

Pygame How To Use Collision?

Can someone tell me how to implement collision in Pygame? For example I have a sprite called A and another one called B. How do I detect if they collide in Pygame?
9
votes
4answers
5k views

2D Spatial partitioning alternatives to spatial hashes and quadtrees

I've been trying to implement a spatial partitioning algorithm in my game, but both spatial hashes and quadtrees aren't what I'm looking for. My level size is not supposed to have a limit (only Int32 ...
-1
votes
1answer
300 views

Insert object at index, when two objects collide

I have two arrays: one for projectiles, and one for targets. Every target and every projectile has tag, and a tag with color (source code I took from Ray Wanderlich). In my small game, when a ...
20
votes
6answers
3k views

Collision 100% avoidance implementation

I'm an absolute beginner with game development and all I know about collision avoidance/resolution, I learnt it on or through this site in the past week... so don't hesitate to correct me if what I'm ...
2
votes
2answers
361 views

Handling collision with 2D surfaces and player sprite

What's the best way of representing surfaces in a 2d top down racing game? I'd like paved and dirt surfaces in my game to have different friction properties. Would you break up the map into a grid and ...
2
votes
4answers
4k views

How do I detect pixel-level collision using andEngine?

I'm developing a game for Android using andEngine, and I need to detect collisions only when two objects visually collide (not in blank space of the image). In J2ME, I'm able to do that using ...
10
votes
1answer
766 views

Are there well-known algorithms for fitting a polygon to an arbitrary shape?

I'm using the Chipmunk physics engine to make the levels for a 2D C game. I'd like to be able to fit a polygon to an arbitrary shape to serve as the collision mask. Given a black and white collision ...
5
votes
2answers
825 views

Collision response for 2D racing game

The title is fairly self-explanatory. I have a 2D racing game that utilizes per-pixel collision detection (the track is essentially two bitmaps, one for the graphics, one for collision data). The ...
47
votes
7answers
5k views

2D Platformer AABB collision problems

I have a problem with AABB collision resolution. I resolve AABB intersection by resolving the X axis first, then the Y axis. This is done to prevent this bug: http://i.stack.imgur.com/NLg4j.png ...
2
votes
2answers
934 views

Tile based map and collision; getting stuck

I'm trying to make my character move around a tile map with collisions. Everything works fine except for one thing. I show you a picture with the problem: http://i.stack.imgur.com/ZWI7x.jpg That is, ...
1
vote
1answer
423 views

How can we match polygon data structure with a background image

I am referring to this fireball game. The ball will collide with background, which is in polygon form. I was wondering, how I can match my polygon data structure with the background image. Say, I ...
0
votes
3answers
290 views

Collision Error

I am having trouble with collision detection part of the game. I am using touch events to fire the gun as you will see in the video. Note, the android icon is a temporary graphic for the bullets ...
1
vote
3answers
568 views

How does this circle collision detection math work?

I'm going through the wildbunny blog to learn about collision detection. I'm confused about how the vectors he's talking about come into play. Here's the part that confuses me: p = ||A-B|| – ...
0
votes
2answers
568 views

Bitmap & Object Collision Help

Is it possible to detect when an object and a bitmap collide. I have an arraylist of sprites that I am shooting with an image. I tried using this method here but as soon as the bitmap appears the ...
1
vote
1answer
209 views

I need help with specific types of movement

I'm adding movable crates to my game and I need some help with my movement code. The way I've set up my movement code the crate's X and Y are moved according to a vector2 unless it hits a wall. Here's ...
4
votes
3answers
775 views

Building dynamic bounding box hierachies

I've been reading about collision detection and I saw that the first part was a coarse detection which generates possible contacts using bounding box hierarchies. I understand the concept of ...
8
votes
3answers
1k views

How to find 2D grid cells swept by a moving circle?

I'm making a game based on a 2D grid, with some cells passable and some not. Dynamic objects can move continuously, independent of the grid, but need to collide with impassable cells. I wrote an ...
1
vote
1answer
449 views

Normal vector of a face loaded from an FBX model during collision?

I'm loading a simple 6 sided cube from a UV-mapped FBX model and I'm using a BoundingBox to test for collisions. Once I determine there's a collision, I want to use the normal vector of the collided ...
2
votes
3answers
1k views

Detect click on Triangle and Circle buttons

How can I detect clicks on a texture (which will be a button in my game) which has the form of a triangle or circle. I only know the rectangle solution which uses the position, width, and height; ...
8
votes
2answers
390 views

Platform jumping problems with AABB collisions

See the diagram first: When my AABB physics engine resolves an intersection, it does so by finding the axis where the penetration is smaller, then "push out" the entity on that axis. Considering ...
3
votes
2answers
2k views

3D Ball Physics Theory: collision response on ground and against walls?

I'm really struggling to get a strong grasp on how I should be handling collision response in a game engine I'm building around a 3D ball physics concept. Think Monkey Ball as an example of the type ...
8
votes
5answers
4k views

How do I detect the direction of 2D rectangular object collisions?

After this question, I need some more help. How can I find out which side of a rectangle a collision came from and react accordingly? The blue arrows are the paths that some circular objects ...
0
votes
1answer
401 views

What maths should I learn for game programming, and what aspect of programming does it relate to? [duplicate]

Possible Duplicate: What math should all game programmers know? Obviously a good knowledge of maths is essential for good programming, my maths isn’t the best ( I didn’t pay attention in ...
1
vote
2answers
8k views

Tips for writing 3D Collision detection with opengl

I would like to any tips/articles/tutorials on how to write collision detection using OpenGL and C++ in 3D mainly just simple box collisions etc but also if there are any advanced resources that would ...
1
vote
1answer
316 views

How are trajectories calculated and transmitted to other players in Multi-Player?

I play alot of COD4. And can see tracers for gunfire, missles, care packages fall from helicopters etc. There is alot of activity. I am curious to know the algorithm (at a high level) that manages ...
1
vote
1answer
579 views

XNA Automatic Collision detection from model?

This is going to be a rather vague question xD In XNA is there a way of working out if a point or rectangle is colliding with a 3D .x object? It is a big model, and would take a long time to map out ...
2
votes
2answers
193 views

Collisions between players at spawnpoints

I am working on a FPS/MMORPG and ran into a problem at spawnpoints, when I enabled collision detection between players. Neither player would be able to move if both spawned at the same time, because ...
1
vote
1answer
243 views

How can I know in which direction 2 balls will go in billiard game?

When a ball is struck, how can we know in which direction both balls will go when ball is struck? I know the angle at which the ball strikes the other ball matters, but how can we calculate that ...
0
votes
1answer
2k views

Java/Android pixel perfect hit detection

I am making a game for android which I need hit detection between two objects. The first bitmap I have is a flying superhero, and the second bitmap is anything that he collides with. The superhero ...
1
vote
2answers
670 views

Which axis-aligned line does an AABB collide with first?

I am making the collision resolution system for my 2d top-down game, and I managed to find a solution where I query which surfaces of other AABBs the current entity can collide with in the next frame. ...
3
votes
4answers
685 views

How to avoid collision detection to enter infinite loop in this case?

I am writing a collision detection system which uses the logic mentioned by Trevor here But I have anticipated a problem which I have shown as a diagram How do we handle this problem?
1
vote
1answer
1k views

XNA boundingbox 2d rectangle

I'm checking to see if the ray that I've created is intersecting with a rectangle. I'm using the boundingbox class to pass the rectangle into the intersect method in the Ray class, but unfortunately ...
1
vote
2answers
825 views

Getting 2D Platformer entity collision Response Correct (side-to-side + jumping/landing on heads)

I've been working on a 2D (tile based) 2D platformer for iOS and I've got basic entity collision detection working, but there's just something not right about it and I can't quite figure out how to ...
15
votes
2answers
1k views

Where should collision detection logic be placed?

I am developing a small 2D game engine. The characters have a paint method which currently does the following: Calculate the new position of the character as per its speed, etc. Update the collision ...
7
votes
2answers
3k views

Stuck in Wall after rectangle bounding box collision

Using XNA's built in Intersects() on two Rectangles, I can detect a collision and set my velocity to zero. However, the object is stuck there and can't get out! How can I resolve this collision ...
2
votes
1answer
985 views

How do I determine the collision normal in an axis aligned bounding box collision?

I have a 3d moving box and a stationary box. I can detect collisions ok but now I would like to slide the moving box against the stationary box as a collision response. For this I need the normal of ...
4
votes
1answer
924 views

Closest point on an ellipsoid

I need to know how to get the closest point on the surface of an ellipsoid to another point. I had an idea, but apparently i was wrong, and oversimplfying. What i did was squash the ellipsoid and ...